Bottom hole well sampler



Nov. 16, 1937. G. w. RusLER BOTTOM HOL WELL SAMPLER Filed April 8, 19365 Shee'bS-Shee'l'. 2

Nov. 16, 1937. G w, RUSLER '2,099,080

BOTTOM HOLE WELL SAMPLER Filed April 1938 5 she'zs-sneet 3 .D www Nov.16, 1937. I I G. w RUSLER w 2,099 ,080 BoT'roM HOLE WELL SAMPLER FiledAprfil 8. 1936 5 SheetS-Sheet 4 'III/47,

Nov. 16, 1937. G w RUSLER 2,099,080

BOTTOM HOLE WLL SAMPLER Filed April 8, 1938 5 sheets-sheet 5.

z 70a 77; 7 mi 2 .29 'a 30 v a "w" Patented Nov. 16, 1937 PATENT oFFicsaosaoso Bo'r'roM HoLE wamJ sAMrLEn George W. Busler, Verona, Pa.,assignor to Gulf Research & Development Company, Pittsburgh, \Pa., acorporation of Delaware Application April 87, 1936, Serial NO. 73,385

19 Claims.

This invention relates to bottom hole well samplers, and it comprises atubular chamber adapted to be lowered into an oil well and provided ateach end with valved units having outv wardly closing valves forentrapping fiuids in the chamber as they exist in their natural state inthe well, valve Operating mechanism in the chamber for causing positiveoperation of the valves, said mechanism including an interlock forpreventing operation of one of the valves until the other valve hasclosed and a dashpot for one or for each of the valves to soften theclosing action of the valves; thus avoiding any pressure or volumedisturbance of the fiuids in the chamber relative to the surroundingfluids in the well by the closure of the valves; and it also comprisesmeans in the chamber for enabling measurement of the pressure of. thefiuid entrapped in the chamber without change in volume and means forautomatically setting the valve interlock and the valves by simplyassembling the Valve units to the chamber, one of said units beingprovided with cable supporting means and a trigger mechanism forOperating the valves and the other of said units being provided with amaximum recording thermometer, all 'as more fully hereinafter set forthand as claimed.

It is of importance to acquire accurate knowledge of the physical andchemical characteristics of fluids as they exist in various locations ina pool o rformation and as they exist in the flow string of Wells inorder to solve problems relating to pumping efiiciency and the like andin order to predict with a fair degree of accuracy the changes thefiuids in the oil pool will undergo throughout the life of the well. Itis particularly important to know the quantities and properties of thegas liberated from solution in the oil at various pressures in theformation and in the fiow strings of the wells. With such knowledge itis possible to attain high production emciency in the operation of wellsdrilled into a particular pool or formation. This knowledge is bestobtained by determining the temperature of the fluids as they exist inthe formation by lowering a maximum recording thermometer into theformation at different locations, by securing sample quantities of thefiuid from the formation and flow strings of Wells drilled into theformation as it exists in its natural state except for change intemperature, and by examining the samples so obtained after adjustmentof their temperatures to that at which they existed in the formation orwell string as recorded by the thermometer.

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(cl; rar- 18) To accomplish this purpose numerous forms of apparatushave been developed, adapted to be lowered into a well and entrap asample of the fluid in the pool at the bottom of the well.

With all prior forms of apparatus of which applicant is aware, thesample of fiuid upon examination does not accurately duplicate the fluidin the well from which the sample is taken and therefore figures basedupon the results of an examination of such sample fluids are unreliable.This is for the reason that the fiuid at the bottom of a well, becauseof its high pressure is in an extremely unstable condition. The gas tooil ratio is apt to change instantly upon Sudden jarring of the sampleas by a simultaneous snapping shut of the valves of the sampler. Furtherdlfficulty has arisen in accurately determining the pressure of thefluid sample since this pressure must be taken without change in volume.This is because the fiuid entrapped is composed of both gas and liquidand frequently gas dissolved in liquids, and the gases under theconditions at which they exist do not necessarily obey the ideal gaslaws as to pressure and volume.

A further disadvantage of many prior devices is that external valvecontrol rods are troublesome both in assembling and disassembling thesample, and in catching on joints or obstructions in the well tubingduring lowering and raising of the device in a well.

It is an object of the present invention to provide a sampling devicewhich shall entrap a quantity of fluid at the bottom of a Well inexactly the same physical and chemical conditions as the fluidsurrounding the device during entrapment, and which shall maintain thefluid so entrapped under the conditions existing in the well except fortemperature changes.

A further object of the invention is the provision of a sampling devicein which the valves to 'sampling chamber are positively closed andpressure or volume disturbance of the fluids during entrapment isreduced to a minimum. This is accomplished by the provision of aninterlock in the valve Operating mechanism permitting one valve to closecompletely before the other, and the provision of a dashpot for one orboth of thea valves to insure softness of the closing operation.

A further object of the invention is the provision of a valve Operatingmechanism located entirely within .the sampler with the exception of theusual Operating trigger at the top of the sampler. and which mechanismautomatically sets itself to open the valves upon mere assembling ofthe' sampler parts.l

A further object of the invention is the provision of means in the wallof the chamber in which .the fiuid is entrapped enabling measurementoflthe pressure of the contained fluid without change in its volume.

A further object of the invention is the pro vision of novel means forsecuring the sampler to the end of a cable after valves are set, saidmeans also protecting the trigger from accidental operation duringtransportation of the instrument and during the act of fastening theendl of the cable thereto. w

A further object of the invention is the' provision of a well samplerwhich shall be inexpensive in manufacture, composed of a small number ofparts arranged for unit assemblage and disassemblage and which shall beexceptlonally simple and accurate in operation.

Other objects and advantages of the invention will be apparent from thefollowing detailed description read in connection with the accompanywing drawings, wherein, g

Fig. 1 is a longitudinal sectional view of the top or head portion ofthe sampler and shows the trigger mechanism and top valve assembly;

Fig. l-A is a longitudinal sectionsal view of the middle portion of thesampler and shows the valve interlock mechanism and the arrangement ofthe pressure diaphragm means for measuring pressure within the chamber;

Fig. l-B is a longitudinal sectional view of the bottom or lower end ofthe chamber and shows the arrangement of the lower valve and thermometerwell; i

Fig. 2 is a'view of a. side elevation of a lubricator used inintroducing and withdrawing the sampler from a well, and shows thesamplerv in dotted lines;

Fig. 2-A is a Vertical sectional view of the messenger supporting andreleasing mechanism for the lubricator.

Fig. 3 is 'an enlarged horizontal sectional view taken along line 3-3 ofFig. 1 in the direction of the arrows;

Fig. 4 -is an enlarged, fragmentary, detail sectional view of thetrigger mechanism for closing the valves;

Fig. 5 is a detailed perspective view of the trigger;

Fig. 6 is a detailed perspective view of the trigger spring;

Fig. 7 is a detailed sectional view of the valve interlock showing' theposition of the parts when the valves are in closed position;

Fig. 8 is a horizontal section view taken along line 8-8 of Fig. 7 inthe direction of the arrows;

'Fig. 9 is an enlarged horizontal sectional view taken along line 9-9 ofFig. 1'-A in the direction of the arrows;

Fig. 10 is a reduced, detail longitudinal sectional view taken' alongline lO-III of Fig. 9 in the direction of the arrows;

.Fig. 11. is a view similar to Fig. 10 but with the caep and diapln'agmof the pressure measuring means removed; v

Fig. 12 is an enlarged, detail sectlonal view showing the constructionof the valves and valve seats; and

Fig. 13 is a Vertical section of a modified form of upper valveconstruction showing one arrangement for applying a dashpot to thevalve.

Fig. 14 is a vertical sectional view of a modified form cable tie fo'rthe instrument. f

Fig. 15 is a side elevation of the tie shown in Fig. 14 with the capshown in vertical section.

Fig. 16 is a detail side elevation of the body of the tie shown in Figs.14 and 15.

Fig. 17 is a side elevation of the member shown in Fig. 16 and Fig. 18is a horizontal section taken along line IB-IB of Fig. 16 looking in thedirection of the arrows.

Referring to the drawings wherein like numerals indicate correspondingparts throughout the several views, the numeral designates the samplereceiving or collecting chamber of the instrument provided with upperand lower out-'- wardly closing valves 2 and 3 respectively. Thesevalves are substantially identical in structure and operation, bothbeing of the mushroorn type and consisting of valve stems 4 and 5 towhich are secured double inverted, frustro conical shaped valve headsprovided with annular knife edge4 projections 6 and for engaging softaluminumshown. Valve seats 8 and 9, respectively, are held inpositionagainst internal Shoulders H and l5 in members iii and |2 by theexternally threaded ends ofvmembers I! and 13 engaging the internallythreaded ends of members Ill and |2 as shown. Valve unit members H and|3 are provided with valve stem guides IB and l'l cast integrallytherewith and supported by spiders (not explained.

The trigger mechanism for Operating the valves' is arranged as a unit ona base or bracket member 23 held in the head by machine screws 24.Projecting from the base are standards 25 extending downwardly to apoint adjacent the end of valve stem 4. (Figs. 1 and 3.) The standardssupport a lever 26 pivotally connected thereto as at 21 and extendingacross the end of the valve stem. To hold the valve off its seat thelever is normally held against the end of the valve stem by the longerarm of a bell crank 28 which ispivotally carried as at 29 on the base'of the trigger mechanism. The short arm of the bell crank extendshorizontally to a point beneath a -trigger .pin or plunger 30 passingthrough the head and projecting slightly above the top of the head. Thispin is arranged for limited Vertical movement in the headby theprovision of an enlarged portion 3| in counterbore 32. The counterboreis closed at its lower end .by a screw collar 33 through which the pinpasses. A spring member 34 .secured to the trigger base by means ofscrews 35 engages through its arms 36 with transversely extending lugs31 on each side of the end of the long arm of the bell crank to maintainthe crank in engagement with lever 26 and hold valve 2 open. In thisposition the short arm 'of the bell crank engages the lower end of thetrigger pin and forces the pin upward through the head of the instrumentin position to be struck by a messenger 38 on cable 39 supporting theinstrument. The sampler is secured to the end of the cable by passage ofthe cable through an openaoeaoeo mg m nie center of the head of themammet where it is first bent slightly on -a large radius about a camshaped member 40, to avoid creation 'of superimposed bending stresses inthe cable.

Member 40 is held in the head of the instrument by a pin or screw 4| andhas a small radius hub i portion (not shown) on which the cable issubseclamping under the head of the screw.

On the end of valve stem guide H for th lower valve `3, a combineddashpot 08 and thermometer well or housing M is secured as at 45. Thedashpot is adapted to 'receive the lower end of valve stem 5 andcontains a light coil spring 45 which engages the end of the valve stemto normally hold' the valve in open position. A small opening 41 in thebottom of the dashpot permits slow leakage of oil from the dashpotduring closing of the valve. 4B is a tube containing a maximam recordingthermometer held in housing 4d by screw cap 05. The thermometer may beread or observed through window 50 in the tubing after 4renit'ival fromthe housing. The lower end of the instrument including* the thermometer-well or housing is protected by a cap or foot piece 5| .which screws onthe externally threaded end of valve unit. coupling member |3. This footpiece is open at its lower end as at 52 and provided with screens 53held in position by castellated, externally threaded ring shape member54. As so far described it will be seen that when the valves Z and 3 areopen and the sampler submerged in fluid in .the well the well fluid maypass freely through the length of the entire instrument, enteringat thebottom through screens 53 and 'leaving at the top through screenedopenings zi.

The valves are forcibly closed by a mechanism hereinbefore referred toas the valve interlock,

located in the sample receiving chamber of the instrument. The interlockconsists of push rods 55 and 56 arranged to slide, one within the otherin a spider supported bearing member 51,' secured within the chamberabout midway between the valves by means of screws 58. The opposite endsof the rods are carried in spider supported beara tubular extension orsleevelike member 56' which passes through bearing 51 and has fltted toits reduced end 51 against shoulder 58' a spring end retaining collar69. The end of push rod 55 has a reduced portion 10 having a sliding fitwithin tubular extension 55 on push rod 55. Shoulder 1| formed on rod 55by this reduced portion serves as a seat against which second spring endretaining collar 12 is seated and a coil spring 13 positioned betweenthe collars tends to force the push rods apart or in oppositedirections. The extreme end 14 of push rod 55 is still further reducedin diameter where it slides in that part of extension 66 in the bearing51. In order that one of the push rods may -move to close its valveprior to closure of the other valve by the second push rod, the top endportion of bearing 51 is enlarged as at 15 ,and a series of vcircularopenings 1| are provided in' sleeve 05 adiacent the enlarged portion ofthe bearing for reception of hardened steel balls 11. These balls are ofgreater diameter than the radial distance from reduced portion 10 to theouter surface'of sleeve 50 so 'that sleeve 6518 held against downwardmovement by jamming of the balls in the opening against taperedshoulders 10 formed in the bearing at the bottom of the recess.Howevel', push rod 55 may move upwardly to close top valve 2 and in sodoing its reduced end portion 16 moves beneath the balls. Coil spring 13then aots to force the balls through the openings 15 and against end 'llout of contact with the shoulder formedin the recess, thus permittingsleeve 05 to move downwardly carrying the balls with it to close lowervalve 3. 19 is a small oil opening in -sleeve 0B for lubrication of theinterlock and is a retaining washer fitting within enlarged opening 15.

Provision is made for measuring the pressure of the fluid entrapped inthe sampler without changing its volume by permanently mounting apressure diaphragm assembly in the chamber accessible from the loutsideof the chamber through opening This diaphragm assembly consists theopening and secured to the wall of the chamber by screws 53. This jointis best sealed against leakage by soldering or welding or lthe like.Against the inner surface of opening 84 through the body member apressure diaphragm 85 is clamped by means of a cap 86. Cap 86 isslightly relieved on its inner side opposite' the diaphragm as shown at81 Vand is provided with perforations 88 for permitting the pressure ofthe fluid entrapped in the chamber to exert inself against the innerface of the diaphragm. On the inside of body member 02 and electricallyinsulated from it is a thimble 88 carrying contact screw 90 -for makingelectrical contact with the inner face of the diaphragm. This thimble issupported in porcelain 9| or other insulating material held in insideflange 02 on the body member perforated as at 03 to permit pressure tobe applied exteriorly to the diaphragm. Access to the contact screw andto the diaphragm through perforations 00 is had by removing the screwlplug 94.

of a flanged body member 02 projecting through For the purpose ofdescribing the operation of the sampler it will be supposed that thesampler has just been emptied of its contents, disassembled. cleaned,and the valve seats renewed. The valves are set lin open position'during assembly asfollows. The lower valve unit is first attached to thechamber i. Before attachment a blind cap is screwed to the end of valvestem guide |1 in place of the thermometer well M. so as to hold valve 3clear of its soft aluminum seat and in its regular open position withrespect to this seat. Durlng attachment of the lower valve unit to thechamber I the head of valve 3 strikes the lower end of push rod 55 andforces it upward against the action of spring 13 moving the balls 11 inthe interlockopposite the enlarged opening 15 in the bearing 51. Theupper valve unit with the trigger set as by depressing the plunger ortrigger pin 30 with the finger and tilting the head so that lever 26falls into position against the end of valve stem l, is 'then screwed onto the chamber. During attachment the head of valve 2 strikes the end ofpush rod 55 and forces it downward against the pressure of spring 13 andat the same time reduced end 10 on the push rod forces the balls 11 intothe enlarged opening 15 of the bearing and holds them there thus thethermometer reset and placed in the well and the well attached to thevalve guide in place of the cap. The lower end or foot piece of theinstrument is then screwed on to the bottom valve unit. Next, theAdiaphragm contact screw 90 is adiusted so that it just contacts thediaphragm when the diaphragm is in its neutral position. The cable-isthen attached and the instrument lowered into a well, to the bottomthereof or to any point in the flow string at which it is desired totake a sample. At this point it may be advantageous to describe one formof apparatus, illustrated in Figs. 2 and 2-A of the drawings, useful inintroducing the sampler into 'a well. This consists of a pipe 95 calleda iubricatorwhich is adapted to be screwed to gate valve 90 at thecasing head of a well. The lubricator is longer than the sampler and hasa branch pipe 91 leading off from thelower end thereof with a pressuregage 90 and a throttie valve 99 mounted therein as shown. At the upperend of pipe 95 a pulley is supported on an'arm |0| carried by pipe 95.The end of the cable is guided over the pulley through a stuiilng box|02 and down through a messenger 103 concentricaliy support.- ed in theupper end of lubricator pipe by means of a guide block m rigidiy securedto the inside wall of the vlubricator by stud bolts |05. The messen'geris releasabiy supported in clamping engagement with the guide member bymeans of hand wheel operated set screw |06. When desirable the messengermay be threaded on and.

off the cable by passing the cabie through a helical slotted opening|0`| in the side of the messenger. The end of the cable is secured tothe sampler. The sampler is then drawn upward' into the iubricator andthe lubricator screwed on to gate valve 90. This valve is then openedand the sampler lowered into the well. During low'- ering of the samplerin the wellI the vaives being open, well fluid caused by lowering of thesampler or by convection currents or ebullition of gas passes throughthe sampler. When the' desred location for the taking of a sample hasvbeen reached the sampler is allowed to remain motioniess for a periodof some 20 minutes or longer or until the surroundng and contained wellfluid reaches a state of uniformity. When it is thought this stage hasbeen reached. the messenger is released from the lubricator by operationof hand wheel 106 and slides down the cable striking the plunger 'ortrigger Operating pin 30 to'release lever 26 from engagement with thebell crank or trigger and allow spring 13 to force valve 2 closed.piained releases the balis 'I'l in the interiock from the Shoulders 19and allows the spring to close valve 3. Closure'of valve 3 however is:resisted by slow escape of oil from dashpot', through opening so thatthis valve closes slowly. The purpose of this is to provide an intervaiof time Closure of valve 2 as exaooaoeo provided with a small opening[05 for slow escape of oil entrapped by the piston.

After both valves have been closed the sampler is withdrawn from thewell, foot piece 5| removed, and the temperature of the well fluid 'atthe point at which the sample was taken noted by reading the maximumthermometer.

The sampler is then heated to this temperature i and the pressure of thecontained fluid measured by connecti'ng the body of the sampler and avolt meter in series in an electric circuit, through electrical contactscrew 90 and diaphragm 05. External fluid pressure is then applied tothe diaphragm through perforations 93 in body member 82 until thediaphragm is moved siightly to open the electric circuit or break itselectrical contact with the contact screw as indicated by the Voltmeter. The external fluid pressure recorded by a gauge in the pressureline at this instant will be substantially exactly equal to the pressureof the entrapped fluid provided the contact screw just contacts 'withthe diaphragm and doesnot exercise pressure against the diaphragm todisto't it or is not spaced from the diaphragm so' that the diaphragm isdistorted by the pressure of the entrapped fluid. Under these conditionslany difference in pressure between the making and breaking points ofthe circuit will be caused by the stiffness or rigidity of the diaphragmitself and with a suitable diaphragm will be so small as to bepractically indiscernlble on the pressure gauge. This is so particularlyin view of the fact that current fiowing in the circuit is verysmall andan almost imperceptible movement of the-'diaphragm serves abies unitconstruction of the sampler since it,

together with the spring. push rods and sampler body portion constitutea "motor" unit from which the valve units may be easily removed andseparately assembled and disassembled. This greatly simplifies theconstruction and operation of the sampler and is important because ofthe necessity for renewing the soft metal valve seats each time thesampler is used.

In Figs. 14 to 18 inclusive, I have shown a modified form of cable tiewhich is particularly adapted for use with the sampler. Referring tothese flgures the numeral |08 designates the head on the top end of thesampler in' which the trigger '30 is mounted as before described and towhich cable 39 is secured. Head |08 is provided with an extended,externally threaded portion 109 to receive a protecting cap 0 for thetie. The protecting cap projects above the top of the' head and has anopening il'l therethrough for passage of the trigger and the cable. Thisopening is of considerably greater diameter than necessary to receivethe cable and trigger but is of smaller diameter than the diameter ofmess'enger |03.

The purpose of this large opening is to avoid swagging or burring of themetal close to the trigger by impact force of the messenger sent downthe cable. Swagging or burring of the cap at this point would cause thetrigger. to bind or stick. With the above construction the impact ,forceof the messenger is absorbed almost entirely aoeaoeo by the. top of thecap since the trigger itself offers little resistance to the downwardmovement of messenger and any swagging or burring of the metal of vthecap around opening Ill is remote from the trigger and cannot cause thetrigger to bind or stick. A further advantageof this construction of tleis that the trigger and valves -of the instrument may be set inoperative position some distance from the place where the instrument isto be used and before securing the instrument to the end of the cable,and the cap unscrewed partly or until it extends beyond the end of thetrigger to shieid and .protect it from accidental operation. The samplermay be transported and handled in this condition without danger ofaccidental firing of the trigger. Immediately before using the samplerthe cap is screwed down tight to expose the end of the trigger forstriking by the messenger.

The tie itself is made in head-piece IBB and consists of a relativelylarge diameter hub member M2 about which the cable is wound for snubbingthe line pull on the cable, an annular groove M3 encircling the headbelow the hub member for receiving the cable from the hub member and aset screw H for final fastening of. the end of the cable. The set screwand the hub member are positioned in a recess in the side of the headand the cable is passed downwardly to the hub member through an openingin a projection overhanging the recess as shown.` A pin ||5eccentrically located in hub member U2 and passing into the headprevents the hub member from turning.

In this form of tie as in the construction of tie first described theline pull on the cable is first snubbed by winding the cable about alarge radius hub in a plane passing through the length of the cableabove the ti`e 'and then is further snubbed by passing the cable aroundthe head in the annular groove so that little or no line pull'remains toloosen the final clamping at the set screw or fracture the cable whereit bends sharply around the screw.

What I claim is:-

1. A well sampler comprising a tubular casing, a valve in said casingadjacent each end thereof, said valves forming a sealed chamber with thecasing when closed, closure. means in the chamber for each of saidvalves, means positioned in the casing for releasably holding the valvesin open position, and means in the chamber operable by a predeterminedmovement of one of said 'valves for Operating the closure means for theother of said valves.

2. A well, sampler comprising a tubular casing, valves adjacent each endof said casing,saidvaives forming a chamber with the casing when closed,

closure means in said chamber for each of said valves, means in thecasing for releasabiy holding the valves in open position, and means inthe chamber operable by a predetermined movement of the closuremeans forone of said valves 'for operating the closure means for the other ofsaid valves.

3. A well sampler comprising a .tubular casing, a valve in said casingnear each end thereof, push rods in said casing for Operating thevalves, each of said push rods being normally fixed against movement,means for actuating the push rods upon their release, means in thecasing for releasing one of said push rods and means in the casingoperable by a predetermined movement of said released push rod forreleasing the other of said push rods, whereby the push rod actuatingmeans is effective to operate one push rod subsequent to a predeterminedmovement of the other push rod.

4. A well sampler comprising a casing, a portion thereof forming achamber for the collection of samples, a valve seat at each end of saidchamber and valves for'said valve seats, push rods in the chamber forseating the valves, the push rods being normally fixed against movement,means for operating the push rods upon their release. the push rodsbeing associated with each other in sliding arrangement, means forreleasing one push rod to' permit the push rod operating means to moveit a predetermined distance with respect to the other .rod and meansassociated with the two rods for eifecting release of the other rod uponsaid predetermined movement, whereby the push rod operating means willthen operate to move both push rods to permit them to firmly seat thevalves.

5. A well sampler comprising a tubular casing, a valve in said casingnear each end thereof, said' valves defining a chamber in the casing,push rods in said chamber for closing the valves, said push rods beingmovable .in opposite directions to close the valves, adjacent ends ofthe push rods being in telescoping engagement, a collar disposed on theendv of each push rod, a spring on said push rds adapted to becompressed between said collars to move the push rods in opvpositedirections and means in the chamber operable by a' predeterminedmovement of one of said push rods for releasing th'e other of said' pushrods for movement by the spring.

6. A well sampler comprising/a tubular member open at its ends, a valvenear each end of said member, said valves when closed being.

'the valves until the other valve has closed.

7. A well sampler comprising a tubular casing, a pair of oppositelydisposed vvalves in said casing spaced apart to provide a chambertherebetween, push rods for closing the valves, a stationary guide forsaid push rods, the ends of said push rods being slidable one on theother 'in said guide,

shoulders on each of said push rods, a spring on said push rods' adaptedto be compressed between said shoulders, said spring tending to forcethe push rods in opposite directions to close the valves, a recess insaid guide, a key in one of said push rods'adapted to engage the guideat said recess to prevent movement temporarily of ;said push rod withrespect to the guide, and a cut away portion adjacent the end of theother push rod adapted to receive said key upon movement of said rod apredetermined distance, whereby upon such movement the key will leavethe recess in the guide and enter the cut away portion on the other pushrod and both rods will be free to move under pressure of the spring inopposite directions to close the valves.

8. A well sampler comprising a tubular casing, upper and loweroppositely disposed valves in said casing spaced apart to provide achamber therebetween, upper and lower push rods in said chamber forclosing said valves respectively, 'a stationary guide in said chamberfor said push rods the ends of said push rods being in telescopingengagement, the upper within the lower, in

'said guide, shoulders on said push rods, a coil spring on said pushrods adapted to be compressed between said shoulders, said springtending to force the push rods in opposite directions to close thevalves, a cylindrical -recess 'in said by the lower` push rod is heldfrom moving to close the lower valve until the upper` push rod has moveda predetermined dlstance to close the upper valve.

9. A well sampler comprising a tubular casing, valve assembly unitsadapted for attachment .to

the ends of said casing, valves and valve seats' in said' units adaptedto form a sealed chamber with. said casing when the valves are closed,

means positioned in one of said valve assembly units for'releasably'holding the valve in said unit ofl its seat, means for resilientlyholding the valve in the other unit oif its seat. spring motor means insaid chamber for closing said vvalves and means in said chamber operableby apredetermined movement of one of said .valves for operating thespring motor ciosure 'means for the other of said valves.

'10. In combination, a well sampler whereln a sample of well fluid isentrapped under pressure within a valve chamber and means permanentlyassociated with said chamber for determining the pressure of the fluidentrapped therein, said means comprising a pressure-responsive diaphragmin the wall of said chamber, one side of said diaphragm being exposed tofluid :pressure within the chamber, an electric contact screw adjustablewith respect to said diaphragm to contact therewith, and means forapplying external pressure to the other side of said diaphragm tobreakits 'electrical contact with said screw whereby the 'external pressurerequired to break said 'contact is substantially equal to the pressureof the contained sample of well fluid.

11. In an instrument designed for actuatlon subsequent to its being.positione'di in place and arranged to be suspended in place by means ofa cable attached thereto and having trigger mechanism operated by meansof a messenger sent alongthe cable, a protecting cap and 'messenger stopfor said instrument having an opening of less idiameter than thediameter of the messenger through which the cable extends and throughwhich the trigger projects when set, the

'opening being of sufilcient size to' accommodate' both the cable andthe trigger and to leave room between them 'and its edge whereby themessenger may strike the trigger to operate it and then expend itssurplus impact force against the cap and any burring of the top or edgesof the cap duel to impact with the messenger will not interfere with'theoperation of the trigger.

12. In an instrument adapted to be suspended at the end of the cable andprovided with a trigger projecting therefrom and adapted to be operatedby a weight sent down the cable, a protecting device for said triggerhaving an opening through which the trigger passes and means for movingthe protecting device on said instrument with respect to the setposition of the trigger to expose it above said opening when theinstrument is in position for operation by the messenger and to concealit beneath said opening to guard it against accidental operation whenthe instrument is not in position for operation.

. 13. An instrument to be suspended in the well or the like by means ofa'cable and having trigger mechanism operable by a messenger sent downthe cable when the instrument is in position.. a guard member threadedto the instrument and having an opening at the top through which thetrigger and the cable pass, the threaded connection between theinstrument and said guard member being such as to permit extension ofthe guard member above the top of the trigger to prevent accidentalmanipulation uthereof until the instrument is ready for use.

14. A-well sampler comprisin'g a tubular casing, valve assembly unitsadapted for attachment to the ends of said casing, valve and valve seatsin said units adapted to form a sealed chamber ,2

with 4 said casing when the valves are closed, means positioned in oneof `said'valve assembly units for releasably holding the valve in saidunit. off its seat, means for releasably holding the valve in the otherunit off its seat, spring motor means in said chamber for closing saidvalves and means in said chamber operable by a predetermined movement ofone of said valves for operating the spring motor means for closing theother valve.

15. A well sampler'comprising a tubular casing, a valve in said casingadiacent each end thereof, said 'valves being adapted to form a sealedchamber therebetween when closed. valve tripping mechanism in saidcasing for one of said valves, valve tripping mechanism in said chamberfor the other of said valves and means convne'cting said valve trippin'gmechanisms so that upon actuation of one of said mechanisms to trip ,itsvalve, the other mechanism is caused to act to trip its valve, and meansfor closingsaid valves after release by said tripping mechanisms.

16. A well sampler comprising a' tubular cssingj a valve in said casingnear each end thereof, said valves defining a chamber with the casingwhen closed, push rods for closing the valves, said push rods beingmovable in opposite directions to close the valves, adjacent ends of thepush rods being 'in telescoping engagement, a collar disposed on eachpush rod near the ends thereof, a spring on said push rods adapted to be'compressed between the collars to move the push rods in oppositedirections, means for holding said push rods in retracted position tocompress the spring and means operable by a predetermined protractedmovement of one of said push rods for releasing the other push rod formovement by the spring.

17. A well sampler comprising a tubular casing, a valve in said casingnear each end thereof, said valves deflning a chamber with the casingfor entrapment of a sample of well fluid, rods for each of said valvesadapted for movement of the valves to closed position and means,releasable upon a predetermined movement of one of the rods, for holdingthe other rod motionless during said predetermined movement of the firstnamed rod whereby said second rod is released to close its valve'subsequentiy to the ciosure of the other valve by the first rod.

18. In a well sampler having a chamber adapted to receive a sample ofwell fluid and valves at each end of said chamber for entrapment of wellfiuid in the chamber, means for holding the valves in open position andmeans for positively p s,ooo,o8o 7. whereby one of the members is heldinv inoperative position until the other member has moved apredetermined distance to close its valve.

19. In a well samplerhaving a chamber adapted to receive a sample ofwell fiuid and valves at each end of the chamber for entrapment of wellfluid inthe chamber, means for holding the valves in open position andmeans for positiveiy closing' the valves, said latter meam comprisinga'closure member for each of the valves and means connecting saidmembers whereby one o! the members is held ininoperative position untilthe other member has moved a predeter- 5 mined distance to close itsvalve.

` GEORGE w. Rusi-ER.

